Method and apparatus for making carrying bags and a carrying bag product

ABSTRACT

Synthetic plastic bags are produced and goods packaged therein by forming a series of bags individually complete but successively connected in, yet easily torn off from, a long strip wound as produced into a supply roll shipped to the point of use, the strip being unwound to present each successive bag dependently and with mouth open to a feed chute to receive goods to be packaged. An advancing continuous flattened thermoplastic film tube, produced either by extrusion or by longitudinally folding and seaming single sheet stock, with application of reinforcement for grip hole cut outs longitudinally spaced at the bag height, is transversely seam welded to form the bottom of one bag and, adjacently parallel to the bottom seam, perforated and severed in the respective tube layers to form the mouth top opening of the trailing next bag; the resultant bag strip being wound with the severed side outermost. Bag constructions with and without expansible side folds and also apparatus for manufacturing the former are described.

United States Patent Sengewald [451 Aug. 8, 1972 s41 METHOD AND APPARATUS FOR MAKING CARRYING BAGS AND A CARRYING BAG PRonUCT lnventor: Karl Heinz Seugevvuld, 480i Kunsebeck, Westphalia, Germany Filed: June 29, 1970 Appl. No.: 50,510

US. Cl. ..93/35 R, 53/183, 93/8 R,

. 4 206/58, 229/69 Int. Cl. .L..B3lb 49/04 Field of .,..93/35 R, 35 H, 35 DT, 8

References Cited UNITED STATES PATENTS 3,390,617 7/1968 Cloud et al ..93/8 R 2,281,964 5/1942 Wolf ..93/35 H X 3,060,075 10/1962 Kincaid ..93/35 R X ol o [s1 ABSTRACT Synthetic plastic are produced and goods packaged therein by forming a series of bags individually complete but successively connected in, yet easily torn off from, a long strip wound as produced into a supply roll shipped to the point of use, the strip being unwound to present each successive bag dependently and with mouth open to a feed chute to receive goods to be packaged. An advancing continuous flattened thennoplastic film tube, produced either by extrusion or by longitudinally folding and seaming single sheet stock, with application of reinforcement for grip hole cut outs longitudinally spaced at the bag height, is transversely seam welded to form the bottom of one bag and, .adjacently parallel to the bottom seam, perforated and severed in the respective tube layers to form the mouth top opening of the trailing next bag; the resultant bag strip being wound with the severed side outermost. Bag constructions with'and without expansible side folds and also apparatus for manufacturing the former are described.

14 Clairm, 9 Drawing figures 42' 3a A 39. LB 43 mm 8 m2 SHEET 1 BF 4 INVENTOR KARL HEINZ SENGEWALD BY ATTY's.

PATENTEDAus 8l972 3,682,051

SHEEI 2 0F 4 INVENTOR KARL HEINZ SENGEWALO PMENTED 8 3,682,051

SHEET 3 OF 4 INVENTOR KARL HEINZ SENGEWALD Mia/W 7%? W ATT'Y'S.

PATENTED 81973 3.6 82,051

saw u BF 4 INVENTOR KARL HEINZ SENGEWALD BY ag ww qa w A T T'Y's.

out the process and also to a sack or carrying bag product manufactured by the method. Hereinafter the invention will be described in terms of carrying bags but it is to be understood to comprehend sacks; and so also the term bags to comprehend sacks and carrying bags.

Carrying bags have hitherto been manufactured in such fashion that they occur as individual pieces, which are then stacked upon one another for packaging and shipped to the place of use. Disadvantageously, such carrying bags must be opened by hand for filling with the goods to be packaged; and also picking up of the individual bags by hand to remove them from a stack is comparatively inconvenient. Especially in self-service stores, in which the purchased goods hitherto have been loaded into bags at the check-out or cashiers counter entirely by hand manipulation of the goods and bags, this requires a considerable expenditure of time, thus delaying the service and dispatch of the customers.

It is the general object of the invention to obviate the above described disadvantages and to provide a carrying bag system and packaging system which excels in further advantageous characteristics.

For the attainment of this object, bags are manufac tured, especially from thermoplastic synthetic plastic film, by a method and with a construction such that though the bags individually are completely finished, they are yet successively connected to form a continuous strip at a tear-ofi weakening line of perforations. As the bags are connected in a strip, and are individually fillable, the possibility arises of separating the bags from the strip after filling. Thus, while yet in connected disposition in this strip, successively the individual bags present a mouth opening for filling with goods to. be packaged, and can be separated from the strip through application of a slight tensional or tugging force.

The stowing or packing of the bags for storage, shipping distribution and use is simplified because they are connected, enabling packing and shipping in compact space-saving arrangements, from which at the place of use the successive individual bags are separated from the strip atthe perforation lines. Especially advantageously the strip can be wound into a roll; but also may be fed in zig-zag fashion into a compact stack in which the successive connected bags lie flat upon one another.

If the strip-connected, completed bags are wound into a roll transported to and used as a supply roll at the place of application, and with unwinding of the supply roll, the individual carrying bags are separated from the strip, then particularly advantageously the successive bags can be first filled and thereafter separated from the strip by tearing off along the perforation line.

For this purpose, advantageously the bag strip may be unwound from the supply roll over a guide roller and with the goods being discharged through a chute located above the supply roll, into the successive individual carrying bags; and after introduction of the requisite goods into the individual bag, the bag be separated from the strip.

The invention is realizable with quite diverse types of bag constructions. Especially advantageous is the procedure of beginning with or making a flattened continuous tube of thermoplastic synthetic plastic film; in both tube layers, which become the bag walls, forming grip hole cutouts at longitudinally spaced locations in the regions for the filling opening or mouth; near the cut outs transversely seam welding the tube layers across the entire tube to provide bottom weld seams for respective bags; and, in close proximity to the bottom weld seams, across the entire tube width in one tube wall'providing a transverse tear-0E weakening line of perforations or other weakening for separability, and again over the width of the tube providing an opposed transverse severing cut through the rest of the tube section; the thus obtained completed bags remaining connected in the desired strip form through the bridges between the perforations.

The above described expedients contemplate bag manufacture starting with a tube, which can be a blown or extruded tube; but also it can be formed by starting from a moving continuous flat single sheet web, folding over the web to an incomplete tube, and then longitudinally continuously welding the superimposed margins with one another for formation of the complete tube.

For manufacturing the described strip of individually finished but connected bags, apparatus-wise it is proposed that there be supported, within the longitudinally moving thermoplastic synthetic plastic film tube, a carriage on which fixed knife or counter blades are mounted for cooperation with respective appropriate exterior blades, whereby one tube wall is perforated on a transverse line from the exterior and the other tube wall or remainder of the tube section at an opposed location is transversely cut from the outside; and finally, adjacent the location on the tube of the aforementioned transverse cut and perforation lines,

there be made the respective transverse seam welding connecting the two tube walls to form the respective bag bottom.

The invention is especially advantageously realized in conjunction with a carrying bag construction providing side infolds for expansibility and also having on each tube wall an interiorly disposed grip reinforcement; for despite these structural features, it can be very-simply compactly stowed or packed either fiat or wound. This advantageous side fold construction is attained by starting with a longitudinally moved continuous flat single sheet web, applying grip reinforcements symmetrically on the both sides of its middle longitudinal axis, preferably continuous reinforcing strips; folding the flat web about its said axis to an incomplete tube with the reinforcing strips disposed interiorly; continuously longitudinally welding the two superimposed margins to one another thereby forming a complete tube; then in combination with a carriage as above described disposed in the thus-formed tube, on both tube edges tucking in side folds; then making the above-described transverse perforation line in one wall layer and the opposed transverse severing cut in the other tube wall layer as well as in the side folds; and finally making the described transverse searn welding joining the tube side walls and simultaneously therewith the side folds to form the bag bottom.

The invention is further detailed in the drawings with respect to some constructional examples, but is not limited to the represented constructions but much rather there are further modifications possible lying within the scope of the invention. I

Other objects and advantages will appear from the following description and the drawings wherein:

FIG. 1 shows a strip of carrying bags and one carrying bag separated therefrom;

FIG. 2 is similar to FIG. 1 but shows carrying bags of another construction;

FIG. 3 shows the unwinding from a roll of a strip of carrying bags into a horizontal reach, but with the mouths of several bags nonetheless opened to show orientation;

FIG. 4 represents the filling of an individual carrying bag yet connected to the strip and hanging supported against the roll with mouth opened;

FIG. 5 is a perspective view rather schematically representing the manufacture of carryingbags, and also part of apparatus therefor;

FIG. 6 is a vertical section through an apparatus for manufacture of the carrying bags in accordance with the invention;

FIG. 7 shows in side view and in essentially schematic fashion, a bag filling apparatus modified from that of FIG. 4;

FIG. 8 is a plan view complementing FIGS. S6;

FIG. 9 is a detail of a carriage mounted device.

In FIGS. 1 and 2, wherein similar components or portions of the bags have similar reference numerals applied, there are shown two different types of carrying bags, respectively 10, 10a, 10b and 100, and 20, 20a, 20b and 20c, manufactured in accordance with the invention in a series of indefinite number, usually large, in such fashion that they are individually finished, but connected together in a single strip. The bags of FIG. 1 have infolded side edges for expansibility; those of FIG. 2 are plain, that is, lack infolding.

The common basic structure is achieved in flat tubular stock by having, immediately adjacent each transverse weld seam 11, which as a bottom-weld seam connects the two tube walls 12 and 13 with one another, the one tube wall 12 across its entire width transversely perforated along a perforation line 14, and the other tube wall provided with a transverse severing cut 15 forming the filling opening or mouth of the respective bag. In FIG. 1 the mouth is shown expanded; while in FIG. 2, for clearer representation, the transverse severin g cut 15 at each bag top is shown in arcuate form.

Either before or after the filling of the bag, the individual bag is torn off along the preferred perforation line 14; but another form of tear off weakening can be used or other type of separation can take place.

In the particular packagings represented in FIGS. 1 and 2, each bag is constructed as a carrying bag, and has grip hole cut outs or punch outs 16, 17 through the respective walls in the grip margin just below the mouth edges, for the strengthening of which there are shown on the inside of the respective bag walls reinforcing strips l8, l9 continuous through the bag height, but in FIG. 2 the reinforcements are localized as patches 18a, 19a.

The separated carrying bag at the bottom of each figure shows the upper edge 20 on the opening or mouth edge uneven in consequence of the perforation line in the former tube wall 12, while the other opposed edge 21, corresponding to the cut 15, is smooth.

In FIG. 1, the strip of carrying bags has edge or side infolds forming like bag fold panels 22-23 on one side and 24-25 on the other side. The cut 15 is carried through the, side infolds to the perforated wall, i.e., to the ends of the perforation or weakening line 14, defining the top edges of the infold panels. Also the proportions are so chosen that with the carrying bag lying flat, the reinforcing strips 18 and 19, disposed interiorly on each respective bag wall and extending over the length of the bag, fall between the side folds, i.e., between the fold lines or inner edges between the fold panels of each pair.

Obviously bags, with or without side folds, may have or not reinforcement of the upper carrying bag margin; and likewise, whether reinforced or not, may have the grip hole cut outs or not as may be found desirable for particular use.

FIG. 3 shows the strip or chain of carrying bags wound up into a roll 26 as a compact bag package conveniently stored and transported to the place of use as a supply roll for packaging goods in the individual bags. The bags 10, 10a, 10b are shown as unwound from the roll extended in a horizontal reach and also with the mouths open, though normally in such disposition closed, to represent more clearly the structure and bag orientation. As an example of use for this purpose, FIG. 4 shows how the goods 27 may be introduced into the carrying bag over a sloping chute 28 disposed above the supply roll 26, the end or leading bag being disposed vertically or essentially vertically dependently at the roll, so that it thereby opens itself. After the bag is filled, the individual bag is to be torn 011 on the above described perforation line 14.

As a modification of FIG. 4, FIG. 7 discloses bag filling apparatus in which the supply roll 26 is unwound over a guide roller or cylinder 45 in order to maintain a constantly equal spacing between the chute 28 and the mouth of the pendent bag, as the supply roll is used up and its diameter changes. There is shown a supply or feed belt 46 for carrying the goods 27 to the sloping chute 28. Furthermore the guide cylinder 45 advantageously is constructed to serve as a bag advance cylinder, for incrementally advancing the carrying bag strip by the lengths of the respective bags. This FIG. 7 represents a particularly convenient arrangement for use at check out counters in self-serve stores.

FIG. 5 shows, in a perspective and essentially schematic representation, the manufacture of the carrying bags appearing in FIG. -l, starting from a fiat single sheet film web 29. The latter, coming from a suitable supply roll and guides is directed form the vertical about a web guide roller 47 as a longitudinally moving horizontal web reach, symmetrically to the middle longitudinal axis 30 of which the reinforcement strips 18 and 19, preferably of heavier plastic film or even paper stock, are applied, for example, by cementing or longitudinal seatn welding where appropriate, the roller 48 guiding these strips into position. As methods and apparatus for bonding such strips to the main web sheet are well known, the devices for cementing or welding are not shown. After bonding on'of 18, 19, the moving flat web is folded over about its middle longitudinal axis 30 to form an incomplete tube with the reinforcements l8, l9 interiorly disposed upon one another; and immediately thereafter, the now superimposed free margins 31 and 32 of the original film sheet are longitudinally continuously welded forming seam 33 to complete a flat tube as such.

Next by means including the carriage disposed within the tube as hereinafter described relative to FIG. 6, the tube side edges are tucked in longitudinally to form the side infolds respectively comprised of the folded in panel pairs 22-23 and 24-25 as more clearly represented in FIG. 2. Thereafter are made the transverse perforation line 14in the lower tube wall 12 and the severing cut 15 through the rest of the tube section, i.e., through the upper tube wall 13 and through the side infold panel pairs. Thereafter, as considered relative to the direction of tube motion, before this severing cut 15 (i.e., adjacent to and on the leading side of 15 and the coincidently positioned transverse perforation cut 14) the transverse welding seaming 11 is made through the tube walls l2, l3 and side folds to produce the bag bottom. This orientation or sequence of the cut and bottom seam weld contemplate winding the product strip of bags directly into the supply roll form 26 from which the bags may be unwound in correct disposition for successive filling while yet connected in the strip, as described relative to FIG. 4 and also FIG. 7. The grip hole cut outs l6, 17 are preferably simultaneously cut through both tube walls by conventional means, therefore not shown, at any suitable point, for example before the side infolding at longitudinal spacings equal to desired bag lengths at what become the mouth margin regions of the finished bag.

FIG. 6, in conjunction with FIGS 5, 8 and 9 represents novel aspects of an apparatus for carrying out the above described manufacture. However, in FIGS. 5 and 6 for clarity of representation, there are omitted the known and conventional devices for longitudinal seam welding of tube (see seaming wheel 49 in FIG. 8) bonding reinforcements 18, 19 to the web, cutting holes 16, 17, and mechanism for driving the tube and web in the direction indicated by arrow 42.

In the horizontally extended reach of the completed tube, comprised of the upper tube wall and a lower tube wall, for convenience designated 13 and 12 respectively since the like -numbered bag walls are derived therefrom, there is disposed a carriage 34 mounting the rollers 35, 35a, 35b and 350 in vertically spaced pairs. These carriage rollers are opposed by the respective support rolls 36 to 360 disposed exteriorly of the tube and mounted in a suitable machine frame. This carriage 34, in combination with side infold tucking fingers or blades 50 with or without guided rollers (not represented in FIGS. 5-6; see FIG. 8) is provided to tuck in the aforementioned side folds 22 and 23 on one side and 24 and 26 on the other side; and the frame thereof is elongated through a plate or like extension 37 for mounting other elements. On the end of the latter there are provided (see also FIG. 9) two spaced transverse cutter counter supports as fixed elements supporting the film for cutting and perforation, namely the fore-and-aft-spaced fixed elements 38, 40 which cooperate with the cutting knife 39 operatively disposed exteriorly of and above the tube wall, and with the perforation knife 41 disposed exteriorly of and below the tube wall 12.

After the apparatus station where these transverse cutting and perforating operations are carried out, the progressing tube reaches the bottom welding station represented by the two welding bars 43 and 44, where the transverse seam welding 11 is carried out on the leading side of the coinciding transverse cut 15 and perforation line 14.

I claim: 1. A method for manufacture of sacks and carrying bags from thermoplastic synthetic plastic film, and filling them with goods to be packed, comprising:

providing a continuous flat tube of said thermoplastic film in long indefinite length including two longitudinally marginally connected bag-wallforming layers, and advancing the tube longitudinally; perforating one wall-forming layer with a transverse line of perforations across its entire width to produce a weakening line along which ultimately a finished bag may be torn off with small manual force, and at the same longitudinal location completely severing the rest of the tub along a transverse severing line; thereafter transversely seam-welding through the entire tube thickness across the entire tube width on a line closely adjacent to and on the leading side of the location of the severing and perforation lines thereby to form the seam welded bottom of one bag next to the mouth of the trailing adjacent bag;

said seam welding, severing and perforating being repeatedly carried out at equi-spaced longitudinal locations defining successive bag lengths on the advancing tube;

whereby there is produced a strip of individually complete bags with the walls of adjacent bags arising from said one layer remaining connected through the residual material in the transverse line of perforations:

packing a selected length of the connected strip of bags in space-saving compact layered arrangement as a transportable pack from which individual bags may be successively torn off along respective perforation lines;

transporting the pack to the place of intended use;

withdrawing from the pack one end of the strip with bag bottoms leading; and

successively filling and seperating each individual bag after filling by tearing from the strip along the respective said line of perforations adjacent its mouth.

2. A method as described in claim 1, wherein said selected length is packed by repeatedly folding at the successive weakening lines to place the bags, successively, flat one upon another in the form of a stacked pack. 3. A method as described in claim 1 wherein said length is wound with the said one wall-forming layer innermost and with the bag mouth leading the bottoms into a roll pack, whereby in unwinding, each successive bag is connected to the strip at its mouth end, and presentable with mouth open and accessible for introduction of goods before separation from the strip.

4. A method as described in claim 3, wherein said strip is unwound in a strip reach extending over a guide element spaced from and parallel to said roll whereby each successive bag may depend from said element in a fillable disposition; and the said goods are gravity fed into the mouth of each successive bag over an inclined path above said reach.

5. A method as described in claim 1 including the 6. A method as described in claim 1 including the step of incising grip holes through both tube layers at longitudinal locations corresponding to the mouth margins of the bags being produced.

7. A method for manufacture of sacks and carrying bags from thermoplastic synthetic plastic film, for goods to be packed, comprising:

providing a continuous flat tube of said thermoplastic film in long indefinite length including two longitudinally marginally connected bag-wallforming layers, and advancing the tube longitudinally;

perforating one wall-forming layer with a transverse line of perforations across its entire width to produce a weakening line along which ultimately a finished bag may be torn off with small manual force, and at the same longitudinal location completely severing the rest of the tube along a transverse severing line;

thereafter transversely seam-welding through the entire tube thickness across the entire tube width on a line closely adjacent to and on the leading side of the location of the severing and perforation lines thereby to form the seam welded bottom of one bag next to the mouth of the trailing adjacent bag; said seam welding, severing and perforating being repeatedly carried out at equi-spaced longitudinal locations defining successive bag lengths on the advancing tube;

whereby there is produced a strip of individually complete bags with the walls of adjacent bags arising from said one layer remaining connected through the residual material in the transverse line of perforations;

packing a selected length of the connected strip of bags in space-saving compact layered arrangement as a transportable pack from which individual bags may be successively torn off along respective perforation lines.

8. A method as described in claim 7 wherein said length is wound with the bag mouths leading the respective bottoms into a product, whereby in unwinding, each successive bag is connected to the strip at its mouth end.

9. A method as described in claim 7 including the step of longitudinally infolding the advancing said tube along each margin before the severing and the seam welding are carried out, thereby to produce expansible bags having side margin infolds.

10. A method as described claim 7 including the step of incising grip holes through both tube layers at longitudinal locations corresponding to the mouth margins of the bags being produced.

11. A method as described in claim 7 wherein said tube is advanced about a carriage disposed internally thereof and bearing fixed transversely extending elements cooperating with external severing and weakening-producing means by supporting the film of said tube for weakening and severing.

12. A method as described in claim 1, wherein said tube'sadvan dabo t carri edis sedi t all therer of and b e aring fi xe d tran erselfixtenai g ele ments cooperating with external severing and perforating means by supporting the film of said tube for perforating and severing.

13. A method as described in claim 1 wherein said tube is provided from a web of single layer thermoplastic film stock by longitudinally advancing said web,

symmetrically to the longitudinal web centerline applying respective continuous strips applied longitudinally to said web substantially centered on each longitudinal half of the web centerline as reinforcement means bonded to one side of the web;

folding the advancing web along said centerline over upon itself with said reinforcement means inward to bring the original longitudinal margins into overlying coincidence,

and continually longitudinally seaming the coincident margins thereby to provide the advancing said tube; said method including the further steps of longitudinally infolding the advancing said tube along each margin before the severing and the seam welding are carried out, thereby to produce expansible bags having side margin infolds, and of I incising grip holes through both tube layers and said reinforcing means at longitudinal locations corresponding to the mouth margins of the bags being produced. I 14. A method as described in claim 1 wherein said tube is provided from a web of single layer thermoplastic film stock by longitudinally advancing said web,

symmetrically to the longitudinal'web centerline applying respective continuous strips applied longitudinally to said web substantially centered on each longitudinal half of the web centerline as reinforcement means bonded to one side of the web;

folding the advancing web along said centerline over upon itself with said reinforcement means inward to bring the original longitudinal margins into overlying coincidence,

and continually longitudinally seaming the coincident margins thereby to provide the advancing said tube; said method including the further steps of longitu dinally infolding the advancing said tube along each margin before the severing and the seam welding are carried out, thereby to produce expansible bags having side margin infolds, and of incising grip holes through both tube layers and said reinforcing means at longitudinal locations corresponding to the mouth margins of the bags being produced. 

1. A method for manufacture of sacks and carrying bags from thermoplastic synthetic plastic film, and filling them with goods to be packed, comprising: providing a continuous flat tube of said thermoplastic film in long indefinite length including two longitudinally marginally connected bag-wall-forming layers, and advancing the tube longitudinally; perforating one wall-forming layer with a transverse line of perforations across its entire width to produce a weakening line along which ultimately a finished bag may be torn off with small manual force, and at the same longitudinal location completely severing the rest of the tub along a transverse severing line; thereafter transversely seam-welding through the entire tube thickness across the entire tube width on a line closely adjacent to and on the leading side of the location of the severing and perforation lines thereby to form the seam welded bottom of one bag next to the mouth of the trailing adjacent bag; said seam welding, severing and perforating being repeatedly carried out at equi-spaced longitudinal locations defining successive bag lengths on the advancing tube; whereby there is produced a strip of individually complete bags with the walls of adjacent bags arising from said one layer remaining connected through the residual material in the transverse line of perforations: packing a selected length of the connected strip of bags in space-saving compact layered arrangement as a transportable pack from which individual bags may be successively torn off along respective perforation lines; transporting the pack to the place of intended use; withdrawing from the pack one end of the strip with bag bottoms leading; and successively filling and seperating each individual bag after filling by tearing from the strip along the respective said line of perforations adjacent its mouth.
 2. A method as described in claim 1, wherein said selected length is packed by repeatedly folding at the successive weakening lines to place the bags, successively, flat one upon another in the form of a stacked pack.
 3. A method as described in claim 1 wherein said length is wound with the said one wall-forming layer innermost and with the bag mouth leading the bottoms into a roll pack, whereby in unwinding, each successive bag is connected to the strip at its mouth end, and presentable with mouth open and accessible for introduction of goods before separation from the strip.
 4. A method as described in claim 3, wherein said strip is unwound in a strip reach extending over a guide element spaced from and parallel to said roll whereby each successive bag may depend from said element in a fillable disposition; and the said goods are gravity fed into the mouth of each successive bag over an inclined path above said reach.
 5. A method as described in claim 1 including the step of longitudinally infolding the advancing said tube along each margin before the severing and the seam welding are carried out, thereby to produce expansible bags having side margin infolds.
 6. A method as described in claim 1 including the step of incising grip holes through both tube layers at longitudinal locations corresponding to the mouth margins of the bags being produced.
 7. A method for manufacture of sacks and carrying bags from thermoplastic synthetic plastic film, for goods to be packed, comprising: providing a continuous flat tube of said thermoplastic film in long indefinite length including two longitudinally marginally connected bag-wall-forming layers, and advancing the tube longitudinally; perforating one wall-forming layer with a transverse line of perforations across its entire width to produce a weakening line along which ultimately a finished bag may be torn off with small manual force, and at the same longitudinal location completely severing the rest of the tube along a transverse severing line; thereafter transversely seam-welding through the entire tube thickness across the entire tube width on a line closely adjacent to and on the leading side of the location of the severing and perforation lines thereby to form the seam welded bottom of one bag next to the mouth of the trailing adjacent bag; said seam welding, severing and perforating being repeatedly carried out at equi-spaced longitudinal locations defining successive bag lengths on the advancing tube; whereby there is produced a strip of individually complete bags with the walls of adjacent bags arising from said one layer remaining connected through the residual material in the transverse line of perforations; packing a selected length of the connected strip of bags in space-saving compact layered arrangement as a transportable pack from which individual bags may be successively torn off along respective perforation lines.
 8. A method as described in claim 7 wherein said length is wound with the bag mouths leading the respective bottoms into a product, whereby in unwinding, each successive bag is connected to the strip at its mouth end.
 9. A method as described in claim 7 including the step of longitudinally infolding the advancing said tube along each margin befoRe the severing and the seam welding are carried out, thereby to produce expansible bags having side margin infolds.
 10. A method as described claim 7 including the step of incising grip holes through both tube layers at longitudinal locations corresponding to the mouth margins of the bags being produced.
 11. A method as described in claim 7 wherein said tube is advanced about a carriage disposed internally thereof and bearing fixed transversely extending elements cooperating with external severing and weakening-producing means by supporting the film of said tube for weakening and severing.
 12. A method as described in claim 1, wherein said tube is advanced about a carriage disposed internally thereof and bearing fixed transversely extending elements cooperating with external severing and perforating means by supporting the film of said tube for perforating and severing.
 13. A method as described in claim 1 wherein said tube is provided from a web of single layer thermoplastic film stock by longitudinally advancing said web, symmetrically to the longitudinal web centerline applying respective continuous strips applied longitudinally to said web substantially centered on each longitudinal half of the web centerline as reinforcement means bonded to one side of the web; folding the advancing web along said centerline over upon itself with said reinforcement means inward to bring the original longitudinal margins into overlying coincidence, and continually longitudinally seaming the coincident margins thereby to provide the advancing said tube; said method including the further steps of longitudinally infolding the advancing said tube along each margin before the severing and the seam welding are carried out, thereby to produce expansible bags having side margin infolds, and of incising grip holes through both tube layers and said reinforcing means at longitudinal locations corresponding to the mouth margins of the bags being produced.
 14. A method as described in claim 1 wherein said tube is provided from a web of single layer thermoplastic film stock by longitudinally advancing said web, symmetrically to the longitudinal web centerline applying respective continuous strips applied longitudinally to said web substantially centered on each longitudinal half of the web centerline as reinforcement means bonded to one side of the web; folding the advancing web along said centerline over upon itself with said reinforcement means inward to bring the original longitudinal margins into overlying coincidence, and continually longitudinally seaming the coincident margins thereby to provide the advancing said tube; said method including the further steps of longitudinally infolding the advancing said tube along each margin before the severing and the seam welding are carried out, thereby to produce expansible bags having side margin infolds, and of incising grip holes through both tube layers and said reinforcing means at longitudinal locations corresponding to the mouth margins of the bags being produced. 